First want to start off with I got this car from Copart so previous condition is unknown. I got it with a broke DPFE hose and very slight hesitation. I went and replaced the hose, replaced the spark plugs and took the throttle body off and cleaned it.

When putting it all back together I had even worse hesitation. I then have cleaned the injectors and new O rings, new IAC valve.

I recently rented a fuel pressure gauge:

Upon connecting the gauge it read 0 psi. After keying on and off almost 10 times i made about 10psi. After i tried starting the engine, it built to 30 psi after about 2-3 minutes. When the throttle is pressed in the psi goes from 29 to about 31 then fluctuates when the throttle is released.
While idling in park stays about 29.
When the red vacuum line is removed from the pressure regulator is increases to about 38 psi and stays there. Covering the regulator or vacuum line with my finger has no change on pressure. The line does have vacuum.
While the red hose is disconnected and throttle is applied the psi stays constant at around 38. When the engine is turned off the pressure dipped to 28 and rose to 32 psi within seconds.

After about a minute and half the pressure was 34 psi.
After 2 and half minutes it rose to 36 psi.
After 10 minutes pressure stayed at 36 psi.
After 20 minutes 34 psi
After 30 minutes 30 psi
After 40 minutes 26 psi
After 50 minutes 22psi
After 60 minutes 20 psi
From here i had to return the tool so i cycled it 3 times to build back to 30 psi.

It doesnt seem to hold pressure, but from my limited knowledge it seems the regulator is allowing the pressure to go to up when throttle is applied. Im lost at this point.

 

you seem to be able to maintain ABOUT 30 psi when running... not too bad. Pressure bleeds off slowly after shutdown so the check valve part of the fuel pump might not hold 100%. I assume the first reading of 0 psi was because you bleed off when installing the gauge ? I don't think the fuel pressure is your hesitation.... no codes ?

 

At one point I had a misfire code, but that never came back.

On another note while in park it runs pretty while, as soon as I go into park it hesitates like crazy even when not moving.

 

you replaced the plugs and had to take off the coils during that move.. IM guessing one of the COPS is bad, has a corroded elect plug, or the spring inside the boot did not seat good on the plug...

 

Thats what I thought but I had replaced the boots and springs. I took a multi-meter to each coil and their resistances were all identical, sure one could still be bad. I guess I will have to go test them individually.

 

im not an expert on code readers, but some guys use a real time recorder to see that data.......... my code reader is only good for reading displayed codes AFTER the fact.